Salt hydrolysis and the medium of a solution
Answers are for parents and teachers.
1
Write the net ionic equation for the first step of Na₂SO₃ hydrolysis.
SO₃²⁻ + H₂O ⇌ HSO₃⁻ + OH⁻
2
Al₂S₃ is hydrolysed irreversibly in water. Write the equation.
Al₂S₃ + 6H₂O → 2Al(OH)₃↓ + 3H₂S↑
3
What colour appears when phenolphthalein is added to a K₂CO₃ solution, and why?
Crimson: hydrolysis leaves OH⁻ in excess and the medium is alkaline.
4
Determine the medium of a ZnCl₂ solution and write the first step of hydrolysis.
Acidic: Zn²⁺ + H₂O ⇌ ZnOH⁺ + H⁺.
5
By the book, food spoils quickly in hot weather. How is this linked to hydrolysis, and what other cause is there?
Heating speeds up the hydrolysis of organic substances; in addition, bacteria multiply faster in the heat.